NEW YORK -- Women with bulimia nervosa have self-regulatory neural abnormalities that aren't seen in healthy controls, researchers here said.

Action Points

Explain to interested patients that bulimia nervosa -- typically beginning in adolescence or young adulthood and mainly affecting females-- is characterized by recurrent episodes of binge eating followed by self-induced vomiting to avoid weight gain.

Note that this study showed that neural abnormalities in a brain framework that governs self-regulatory processes are associated with bulimia.

Bulimic women have impaired activity within a brain framework that governs self-regulatory processes, according to Rachel Marsh, Ph.D., of Columbia University and the New York State Psychiatric Institute, and colleagues

The differences were manifested in more impulsive responses on a standard psychological test, the Simon Spatial Incompatibility task, Dr. March and colleagues said in the January issue of Archives of General Psychiatry.

The greater impulsivity was paralleled by different patterns of activation of frontostriatal regions of the brain, as seen in functional magnetic resonance imaging, the researchers said.

The researchers enrolled 20 women being treated for bulimia at the New York State Psychiatric Institute. Twenty non-bulimic controls were recruited from the community.

The Simon Spatial Incompatibility task involves reporting which way an arrow is pointing regardless of whether it appears on the left or right of a screen. The task is easier when the arrow's direction is the same as the side on which it appears -- a so-called congruent stimulus.

The volunteers were asked to signal the direction of the arrow quickly, using different fingers on a response box. Each run consisted of 102 stimuli and the experiment was repeated 10 times, with a total of 68 incongruent and 952 congruent arrows.

The researchers found that the bulimic women tended to respond faster to incongruent stimuli and to get more of them wrong. Specifically:

The average reaction time for patients on incongruent stimuli was 634 milliseconds, compared with 664 for controls, a difference that was significant at P=0.01.

Patients on average got 10.1% of the incongruent stimuli wrong, compared with 7.4% for the controls, a difference that was also significant at P=0.01.

There was no significant difference in reaction time or error percentage for congruent stimuli.

For patients, accuracy on the incongruent stimuli fell on average over the 10 runs of each experiment. Also, those with more severe disease had significantly greater inverse associations with accuracy on the incongruent trials (at P<0.001 to P<0.003, depending on the measure of disease severity used.)

The functional differences were accompanied by different patterns of activity in the brain, Dr. Marsh and colleagues found.

When controls responded correctly to incongruent trials, their responses were associated with significantly greater activity in frontostriatal regions compared with patients, including:

On the left side, the inferolateral pre-frontal cortex (Brodmann area 45) at P=0.004 and lenticular nucleus at P=0.008).

On the right side, the ventral and dorsal anterior cingulate cortex (Brodmann areas 24/32) at P=0.01, the putamen at P=0.01, and the caudate nucleus at P=0.001.

Bilaterally, the inferior frontal gyrus (Brodmann area 44) at P=0.005 and thalamus at P=0.01.

The findings imply, the researchers said, that "self-regulatory processes are impaired in women with [bulimia], likely because of their failure to engage frontostriatal circuits appropriately."

But Dr. Marsh and colleagues cautioned that the impairment could also be the result of chronic illness, rather than the cause.

The study was limited to adult women, they added, and can't be generalized to men or adolescents with bulimia.

It was also limited by the lack of a control group of impulsive individuals with healthy weights and eating behaviors, which would have allowed a more precise assessment of frontostriatal abnormalities in people with bulimia.

The study was supported by the National Institute of Mental Health, the National Alliance for Research on Schizophrenia and Depression, and the Sackler Institute for Developmental Psychobiology at Columbia University. Dr. Marsh reported no conflicts.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine

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